Rapid copper build up under muzzle brake on tip of muzzle

[bubbahotep]

Colt 20" AR15. Brand new had 1-2mm of sewer barrel copper on the tip of my muzzle under the brake, removed that, oiled it up real well and it still came back after the next outing. Ugh. After about 50 qtips I give up and remove the brake to chisel off the copper chunks, it was literally prongs of copper sticking up in the shape of the rifling, black until I start scraping it.

Shape of the copper seems like it's trying to weld the brake onto the muzzle so I'm a little concerned that it'll be incredibly difficult to remove if I let the buildup get too bad as well as it making it difficult to tell when the bores clean.

Anyone ever find a way to manage it? Maybe I can polish or coat the muzzle in some other oil? Seems like it's copper vapor being deposited since it's building up in places where the bullet cannot touch.

Read More

 

[DLS]

By brake do you mean the flash suppressor, or do you have a non-standard attachment on your rifle?

To remove copper buildup just use a copper removing solvent. Follow the instructions as some can be pretty potent but they don't cause any harm to the rifle if used properly. I used Sweet's (https://www.brownells.com/gun-clean...vents/sweet-s-7-62-bore-cleaner-prod1404.aspx), but there are many other brands that have good reviews from their users. The last thing I would be doing is chiseling anything on or near a firearms bore.

If the copper is only found the last few millimeters of the barrel then there is probably a rough spot that will smooth with firing. A little JB's Bore Paste https://www.brownells.com/gun-clean...mbedding-bore-cleaning-compound-prod1160.aspx) is great for a general polish of the bore and can help smooth out the rough area near the muzzle.

I hope this helps.

 

[bubbahotep]

Its thick chunky copper outside the bore on the tip of the muzzle down to the threading. Rifling is clean. Standard ar15 brake/suppressor style, the one Colt put on it. Tried #9 ammonia based and the more aggressive acid based cleaner but it would take hours without scraping, I just used the tip of a brass jag and avoided the crown.

 

[DLS]

Like this?

M16 Flash Suppressor

• DLS
• Apr 7, 2019

 

[DLS]

Hoppe's #9 Copper Solvent is probably the most mild of the bunch. Sweet's is probably the most ammonia heavy with the other's in between. Ammonia is what you want with copper.

If there are really layers and chunks, KROIL is very good about getting under layers and lifting fouling, but lead and copper. I've been in the KROIL / JB's Bore Paste camp for years and it's worked very well for me.

 

[JustSomeGuy]

I would check the crown for tiny burrs. If you can run a dry cotton q-tip around the crown without leaving small clumps of cotton behind, your crown is good.
This sounds almost identical to an issue I had with a DPMS rifle several years ago that was poorly crowned.

 

[bubbahotep]

Yeah it's standard m16 one like above. Builds up in highlighted area. It was so thick I thought it was a crush washer at first but they don't regrow. I should try the kroil and bore paste.

 

[jbett98]

Maybe the end of the barrel isn't milled perfectly perpendicular to the threads. Try coating the muzzle's flat area with red magic marker and reattach the flash hider and take it back off to see if the coloring remains in that area. Dykem machinist blue would also work.

 

[JustSomeGuy]

Regardless of the cause, you should never be getting chunks of copper stripped off of a bullet passing through the bore. I would definitely consider calling colt and discussing it with them.

 

[bubbahotep]

Its not stripped off the bullet, its vapor or gas particles, I get similar buildup on bayonets as well on other rifles.

 

[JustSomeGuy]

Its not stripped off the bullet, its vapor or gas particles, I get similar buildup on bayonets as well on other rifles.

In the original post: "it was literally prongs of copper sticking up in the shape of the rifling". That sounds to me a little more like shavings than it does like the microscopic copper particles we all deal with.

 

[Member 5605]

No pictures?